Communication systems for interfacing with databases have evolved from direct terminal interconnects to systems that communicate through the phone lines via modems, touchtone keypads, etc. In the early years of database communications, a dedicated terminal of some type was required in order to access the database and provide an interconnect thereto for transfer of data in both directions. With the advent of personal computers and modems, various communication software could be utilized to allow access to these databases by a large number of subscribers or users. However, these systems were somewhat restrictive in that they required a computer and access to a phone line, which significantly reduced mobility. Even the use of notebook computers did not significantly increase the mobility of the user when accessing the database since these systems typically require the computer to be set up, programs loaded therein and then access to the database obtained.
In order to increase the mobility of the user, voice prompt and key prompt systems were developed to allow a user to access various databases. For example, voice prompt systems were developed that required the user to enter simple numbers or letters into a phone after dialing the number of the database. These type of systems are restricted to relatively simple access. For more sophisticated systems that require entry of alpha numeric data, one solution to this problem has been to provide a decoder at the database location that can decipher "double hit" keys on a DTMF keypad, wherein a letter is defined as being more than one key depression. For example, the numeric key "2" on a conventional telephone keypad has associated therewith the letters "A", "B" and "C". To select the letter "A" would require depression of the "2" key followed by depression of the "1" key. Selection of the "C" would require depression of the "2" key followed by depression of the "3" key. This is a workable situation, but is somewhat unwieldy in that the user must keep track of the keystrokes. However, some verbal feedback is provided to make the system slightly more user friendly.
Another system provided for communicating with the database is that disclosed in U.S. Pat. No. 4,799,254, issued Jan. 7, 1989 to D. C. Dayton, et al. The Dayton system provides a small data terminal that has a speaker acoustically coupled to the telephone mouthpiece. After a dial-up connection to a central database, a stored message is recalled and transmitted to the database location in the form of sequential pairs of standard DTMF tones. However, this system does not allow access in conjunction with an interactive database, nor does it utilize conventional DTMF tones that are 100% compatible with conventional telephone systems and keypads.